Oil-Free Screw Compressor Seal Layout for Shorter Bearing Spacing
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Solution Overview
Problem
Conventional oil-free screw compressors are complex in configuration, making them difficult to manufacture, and prone to screw rotor bending due to long distances between bearings, which can lead to reduced volumetric efficiency and potential lubricating oil intrusion into the rotor chamber during unload operations.
Innovation Solution
The design incorporates a single atmosphere communication section in the casing that connects both communication sections of the first and second shaft seal devices, allowing for a shorter distance between the screw rotor and bearings, and includes a larger flow passage sectional area in the first communication section to prevent negative pressure-induced lubricating oil intrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separate atmosphere communication sections are formed in the casing to prevent lubricating oil intrusion, then lubricating oil prevention is improved, but device complexity increases and manufacturing becomes difficult
Solution Approach 1:
The patent merges two separate atmosphere communication sections into a single integrated atmosphere communication section that serves both shaft seal devices. This single section includes a first communication portion for the first shaft seal device and a second communication portion for the second shaft seal device, both communicating with the atmosphere through one unified structure in the casing, thereby simplifying the overall configuration while maintaining the function of preventing lubricating oil intrusion.
2Reliability
If two separate atmosphere communication sections are formed in the casing, then lubricating oil prevention is improved, but manufacturing precision requirements increase due to positioning constraints
Solution Approach 1:
By combining two separate atmosphere communication sections into one integrated structure, the patent reduces the number of positioning requirements from two independent sections to one unified section. This single atmosphere communication section incorporates both communication portions with predetermined positions, thereby reducing manufacturing precision requirements and making production easier.
3Reliability
If the distance between communication sections is increased to avoid interference, then atmospheric communication is improved, but screw rotor bending increases due to longer bearing distance
Solution Approach 1:
The patent merges the two atmosphere communication sections into a single integrated section that accommodates both communication portions in close proximity. This unified structure allows the communication sections to be positioned near each other without interference, thereby reducing the distance between bearings and preventing screw rotor bending while maintaining effective atmospheric communication for both shaft seal devices.
Data Source
AI summary
The oil-free screw compressor includes: a screw rotor including a screw and a shaft; a bearing; a first shaft seal device disposed between the screw and the bearing, the first shaft seal device including: a first seal and a first communication section; a second shaft seal device disposed between the first shaft seal device and the bearing, the second shaft seal device including: a second seal and a second communication section; and a first seal member including a seal between the first communication section and the second communication section. The casing includes an atmosphere communication section configured to communicate the first communication section and the second communication section with an atmosphere. A sectional area in the first communication section is larger than a sectional area between the seal of the first seal member and the shaft.